1. Field of the Invention
The present invention relates to a microwaveable container and, more particularly, relates to a container constituted of a microwave transparent material for the heating or cooking of foods or comestibles through the intermediary of microwaves at a high degree of efficiency and with an enhanced temperature uniformity.
In recent years, the heating and cooking of foods through the utilization of microwaves has immensely gained in popularity with homemakers in view of the simplicity and rapidity in the preparation and cooking of various kinds of foods in this manner. Generally, the foods, which may be in a frozen state or at ambient temperature, are heated or cooked in suitable containers, which may be reusable in nature, i.e. Pyrex.RTM. or other non-metallic cookware, or disposable, such as foamed plastic material or the like. Such containers are formed from a material which is transparent to microwaves to enable the foods within the container to be raised to suitable heating or cooking temperature in the absence of any undue heating of the container itself, tending to possibly cause distortions adversely affecting the integrity of the container. Furthermore, during the heating or cooking of the foods in the container through microwaves, the heating of the foods is frequently generally irregular or uneven in nature; in essence, various locations within the container are raised to higher or non-uniform temperatures, causing the formation of so-called "hot spots" thereby resulting in an uneven heating or cooking of the foods and adversely affecting the taste and appearance thereof to a consumer.
In order to attain a high degree of efficiency and temperature uniformity in cooking the foods in containers through the intermediary of microwaves, various steps have been undertaken in the development of microwaveable containers in order to solve the encountered problems. Among these solutions are the use of laminated or complex types of materials for the containers, such as special susceptor materials which will improve upon the microwave efficiency. Furthermore, in order to further ameliorate problems encountered in the nonuniform heating or cooking of foods in containers which are constituted from microwave transparent materials, consideration has been given in the technology towards suitable configuring of the containers, such as raising at least portions of the bottom surfaces thereof such as to distribute the contents of the container in a more optimum or expedient manner, and to thereby obtain a greater degree of temperature uniformity during the microwave heating or cooking process. Although the various measures which have been undertaken in the technology in order to improve upon efficiency and temperature uniformity during microwave cooking of various comestibles, these will still have not proven to be entirely adequate; necessitating, either the employment of expensive materials or container constructions, or configuring microwave-transparent containers in a manner which has still proven to be somewhat elusive in providing the required degree of temperature uniformity during the cooking of the foods.
2. Discussion of the Prior Art
Thus, Matsui U.S. Pat. No. 4,704,510 discloses a container for food service which is adapted to withstand heating in a microwave oven, wherein the container is formed from a laminate sheet material consisting of a non-stretched polyethylene terephthalate film laminated to the interior of a foamed plastic sheet. Moreover, the bottom of the container is raised to curved concavely towards the center thereof in order to distribute the container contents and thereby improve upon the heat distribution within the container during the heating or cooking of the contents with microwaves. However, the laminated container material employed herein is of a complex and resultingly expensive construction.
Bowen, et al. U.S. Pat. No. 4,486,640 pertains to a utensil for cooking and/or baking foods in a microwave oven in which a generally flat bottomed container base incorporates a removable tray and a closure lid possessing apertures to enable the escape of steam which is generated during cooking. This microwaveable container structure is relatively complex and expensive, while it does not enable the optimum distribution of foods or comestibles within the container to allow for a more uniform temperature distribution therethrough during cooking with microwave energy.
Watkins U.S. Pat. No. 4,416,906 discloses a microwave food heating container having a central raised core in the container bottom to essentially distribute the food contained therein about an annulus to improve upon the uniform heating thereof. As in the other above-mentioned patents, there is no optimum distribution of the food within the container so as to allow for a greater efficiency during cooking and a degree in the uniformity of the temperature which will meet the demands of the technology for cooking with microwave energy.
Isakson, et al. U.S. Pat. No. 4,640,838 describes a vapor-tight microwave oven package incorporating a vent enabling the escape of steam or vapor which is generated during cooking, and does not provide for an optimum distribution of foods within a generally rigid microwaveable container to attain uniform temperatures during microwave cooking or heating of the food contents of a container.
Levendusky, et al. U.S. Pat. No. 4,560,850 discloses a microwave container with a cover incorporating a port for the release of steam, and with a raised container bottom to distribute the foods therein for more even cooking or heating. This structure also fails to provide for the optimum dispersion of a food within a specially configured container and does not allow for an adequately uniform temperature distribution through the food as it is cooked by microwave energy with a resultant higher degree of efficiency.
Ragusa et al. U.S. Pat. No. 4,859,822 assigned to a common assignee overcomes all of the above problems. The present application similarly, not only also solves all of the aforementioned problems, but is also an improvement over said U.S. Pat. No. 4,859,822 in that the present shape is more functional for deli-type containers and is more readily acceptable by the industry than Ragusa et al.